A. Field of the Invention
The present invention relates to methods and apparatus for protecting the corners of rectangularly-shaped frames, particularly picture frames, from impact damage during shipping. More particularly, the invention relates to a method and apparatus for attaching protective corners to two adjacent corners of a picture frame in tandem.
B. Description of Background Art
Picture frames for holding and displaying paintings, photographs, diplomas, certificates and similar flat articles are manufactured in prodigious quantities worldwide. Although picture frames vary in shape and construction details, most frames have a rectangular plan view shape. Moreover, the structure of most picture frames consists essentially of four straight channel members or moldings, each having an inner channel that intersects channels of adjacent members at a ninety degree angle. Four such channel members fastened together form a rectangular ring-shaped frame. The channels or recesses in the moldings comprise spaces for receiving a rectangularly-shaped flat display piece such as a photograph or painting, and sometimes, a backing panel, mat and protective cover glass.
Picture frames of the type described above are made from a variety of materials including, wood, metal and plastic. Whatever material the frame is made of, the geometry of a rectangular picture frame dictates that it have four peripheral members of generally uniform thickness which are joined at each other at forty-five degree mitre angles to form ninety-degree corners. These corners are sharp, and are therefore highly subject to breakage, denting or cosmetic damage during shipment. Accordingly, most picture frames, whether empty or occupied, are fitted with some sort of corner protectors during shipment. Such corner protectors are usually made of a relatively inexpensive recyclable material such as cardboard or polystyrene foam. Typical corner protectors of this type are disclosed in U.S. Pat. Nos. 3,955,677, 4,598,825, and 5,447,233. Other patents, related to protecting corners of objects during shipping include U.S. Pat. No. 4,407,898. Also, U.S. Pat. No. 5,255,458 discloses a three-dimensional picture corner and U.S. Pat. No. 4,787,553 discloses a corner fastening device.
In addition to the above-referenced patents related to corner protectors and the like, a variety of machines for bending sheet metal or cardboard of the type used for corner projectors have been disclosed in the following U.S. Pat. Nos.: 4,132,102, 4,585,432, 4,713,957, 4,857,038, 4,956,961, and 5,184,998.
None of the aforementioned references disclose a machine for automatically attaching corner protectors to picture frames. Accordingly, the task of attaching corner protectors to picture frames was formerly labor intensive and time consuming. In response to those limitations of the prior art, the present inventor disclosed an automatic Method and Apparatus For Attaching Corner Protectors to Picture Frames, in U.S. Pat. No. 6,018,934. In that patent, the present inventor disclosed a method and apparatus for installing covers to protect picture frame corners from damage during shipment, utilizing thin cardboard preforms having symmetric, left and right-hand, right-triangular cover flaps joined at vertical sides thereof to opposite vertical sides of a vertically elongated, rectangular spine flap, the left-hand triangular cover flap having depending downwardly from its base a horizontally elongated rectangular side cover flap, and depending downwardly from the lower lateral edge of the side cover flap a trapezoidally-shaped securement flap. The preform is positioned below a picture frame corner, with intersecting side members of the frame vertically aligned with the sides of the left-hand right-triangular cover flap, which serves as a lower face cover flap. The apparatus includes folder mechanisms including flap folder arms which are retractable into recesses provided in a work table, and which are extendible and rotatable to thereby bend the side cover flap and securement flap into a vertical position adjacent a first side of the frame corner and perpendicularly inwardly to overlie the first frame member, bend the spine flap and right-hand triangular cover flap into a vertical position adjacent the second frame member, and bend the right-hand triangular flap perpendicularly inwards from the spine flap to overlie the second and first frame members. An automatic staple gun then inserts a staple downwardly through the right-triangular cover flap into the securement flap and left-hand frame member, securing the corner protector in a folded disposition over the frame corner.
The present invention was conceived of to provide an automatic tandem corner protector attachment method and apparatus characterized by increased throughput rate, and a further enhanced degree of automation over the prior art.
An object of the present invention is to provide a method for attaching in tandem a pair of protective covers to adjacent corners of a picture frame, to protect the corners from damage during transit.
Another object of the invention is to provide an apparatus for automatically attaching in tandem a pair of protective covers to adjacent corners of a picture frame.
Another object of the invention is to provide an apparatus for folding a pair of flat sheets of flexible material over two adjacent corners of a picture frame, and securing the folds of each sheet together to form a pair of separate protective covers, one for each of the two adjacent corners of the picture frame.
Another object of the invention is to provide an apparatus for bending a pair of flat cardboard preforms cut to a pre-determined shape over a pair of adjacent corners of a picture frame, and securing the folded portion of each cardboard preform to thereby form a pair of corner protectors for the picture frame.
Another object of the invention is to provide a picture frame corner protector attaching apparatus which includes means for clamping and holding a pair of adjacent corners of the frame, folding over each corner a separate one of a pair of preform sheets, each having the shape of a truncated isosceles triangle with a trapezoidally-shaped tab depending downwardly from one side of the base of the triangle, into three separate flaps which overlay each of the two corners of the frame, and securing the flaps of each preform sheet together and to a frame molding to form a pair of corner protectors covering the two corners of the frame.
Another object of the invention is to provide a picture frame corner protector attaching apparatus which includes a pair of adjustably spaced apart, mutually perpendicular holding jigs adapted to receive a pair of adjacent corners of picture frames of various sizes, the apparatus including sensor means associated with each of the two holding jigs to provide an index signal indicating that a picture frame corner has been fully inserted into a holding jig in a properly aligned disposition, and logic means responsive to the simultaneous presence of index signals from both holding jig sensors in producing a command signal to initiate attachment of a pair of corner protectors to the adjacent corners of the picture frame.
Various other objects and advantages of the present invention, and its most novel features, will become apparent to those skilled in the art by perusing the accompanying specification, drawings and claims.
It is to be understood that although the invention disclosed herein is fully capable of achieving the objects and providing the advantages described, the characteristics of the invention described herein are merely illustrative of the preferred embodiments. Accordingly, I do not intend that the scope of my exclusive rights and privileges in the invention be limited to details of the embodiments described. I do intend that equivalents, adaptations and modifications of the invention reasonably inferable from the description contained herein be included within the scope of the invention as defined by the appended claims.
Briefly stated, the present invention comprehends a method and apparatus for automatically installing in tandem pairs of protective cardboard covers to adjacent corners of rectangularly-shaped frames, particularly those used to hold pictures, documents and the like, the covers protecting the corners of the frame from damage during shipment.
The automatic tandem corner protector attachment method and apparatus according to the present invention preferably utilizes corner protectors made from thin sheets of cardboard, each pre-cut, by die cutting, for example, into a generally triangular shape which is modified to adapt the preform to be folded over and enclose a corner and adjacent portions of the side channel members of a conventional rectangularly-shaped picture frame. Four such corner protectors are used to cover the four corners of the frame. In a preferred embodiment of the invention, the overall plan view shape of the corner protector preform is that of two mirror symmetric, left and right, right-triangularly shaped flaps having collinear horizontal bases joined to opposite vertical sides of a vertically elongated rectangular spine flap. Thus shaped, the preform has the appearance of an isosceles triangle whose vertex is horizontally truncated. The preform preferably includes a horizontally elongated, rectangularly shaped lower cover flap which depends downwardly from the base of one of the right-triangle flaps, the left one, for example, and has the same width as the left triangular cover flap. A trapezoidally-shaped securement flap depends downwardly from the bottom edge of the lower cover flap, the securement flap having a lower edge wall parallel to but shorter than that of the lower cover flap. In a preferred embodiment, the horizontal width of the vertically elongated rectangular spine flap and the vertical height of the horizontally elongated lower cover flap have a common value which is slightly greater than the thickness of a picture frame which is to protected, e.g., about {fraction (15/16)} inch for a frame thickness of ⅝ inch. Preferably, the vertical side walls of the vertical spine flap and the horizontally disposed upper and lower edges of the lower cover flap are scored to facilitate folding those respective flaps to contact adjacent perpendicular channel members or moldings of a picture frame.
According to the method of the present invention, a pair of preforms, score lines up, are positioned below two adjacent corners of a picture frame. Each of the two adjacent corners of the frame is oriented with respect to a preform with a pair of perpendicularly intersecting adjacent side walls defining a corner of the frame vertically aligned with the perpendicular sides of the left-hand right-triangular flap having the downwardly depending lower cover and securement flaps. The lower cover and securement flaps are then folded vertically upwards as a planar unit along the upper or inner score line defining the junction between the base of the left right-triangular cover flap and the lower cover flap. Next, the securement flap is folded downwardly and inwardly along the lower or outer score line towards a horizontal position contacting the upper surface of the frame member overlying the left triangularly-shaped cover flap. Then, the second, right-hand, right-triangularly-shaped cover flap and spine flap are bent upwards as a unit along the innermost vertical fold line, i.e., the left-hand vertical edge of the spine flap, to a vertical position. The right-hand triangular cover flap is then bent downwardly and inwardly along the outermost, right-hand vertical fold line of the spine flap to a horizontal position overlying and contacting the securement flap. Finally, the overlying right-hand triangular cover flap is fastened to the securement flap, by stapling, for example. In a preferred embodiment of the invention, using a wooden picture frame, a staple is driven through both the overlying right-hand triangular cover flap and the securement flap and into the underlying wooden frame member, thereby securing the corner protector to the frame.
With a preform attached to a corner of a picture frame as described above, the first, left-hand triangular cover flap covers a right triangular portion of the lower side of the frame corner, and the lower, rectangularly-shaped cover flap covers a portion of the outer, vertical side wall of a first side channel member of the frame, e.g., the xe2x80x9cleft-handxe2x80x9d side channel member. Also, the second, right-hand triangular cover flap covers a right triangular portion of the upper side of the frame cover overlying the lower triangular cover flap, while the spine flap covers a portion of the outer, vertical side wall of the second, xe2x80x9cright-handxe2x80x9d side channel member.
The apparatus according to the present invention includes a base plate or work table having a flat upper surface for supporting a pair of adjacent corners of a picture frame, and a pair of frame holder clamping jigs for receiving and holding the adjacent corners of the picture frame on the surface of the table. In a preferred embodiment, the apparatus includes a pair of substantially identical corner protector installation mechanisms oriented at ninety degrees with respect to one another, each including a clamping jig and laterally movably mounted on a supporting frame. This construction allows the lateral spacing between the two clamping jigs to be adjusted to accommodate picture frames of various widths.
Each of the two tandem corner protector installation mechanisms includes a pair of corner protector flap folder actuators positioned on opposite sides of the corner of a picture frame held in the clamping jig. Each corner folder actuator includes a flat, rectangularly-shaped flap-contacting arm mounted near a longitudinal end thereof on the upper end of a post which is actuable by a linear actuator from a lower inactive position in which the arm resides within a rectangularly-shaped recess in the upper surface of the base plate, with the upper surface of the arm flush with the upper surface of the base plate, to an upper, active position. Each post also includes a 90-degree rotary actuator means, which is effective in rotating a flap contacting arm, when raised, from an outer position contacting the outer vertically disposed side of a flap to an inner position effective in exerting an inwardly and downwardly directed folding force on the flap.
In operation, the first corner folder actuator arm is extended vertically, folding the lower cover flap and securement flap upwardly into a vertical position adjacent one side of a frame. The arm is then rotated inwards, bending the securement flap inwardly and downwardly into contact with the upper surface of the first frame molding strip.
Next, the actuator arm of the second corner folder actuator is elevated, folding the upper triangular cover protector flap upwardly to a position vertically adjacent the outer edge of the second frame molding strip. The arm of the first corner folder actuator is then rotated outwardly from its position overlying and holding down the securement flap, while the arm of the second actuator is simultaneously rotated inwardly, bending the triangular flap down into contact with the securement flap. An automatic stapling machine then inserts a staple through the upper triangular flap, underlying securement flap, and underlying frame molding, thereby securing the corner protector to the frame. Both actuator arms are then automatically rotated and retracted to their recessed positions, flush with the work table surface. At the same time, the frame holding clamp is also automatically released, allowing the frame with attached corner protector to be removed from the clamp.
The apparatus according to the present invention includes means for automatically and substantially simultaneously initiating operation of two corner protector installation mechanisms of the type described above, each time two adjacent corners of a picture frame are fully inserted into and correctly oriented with respect to clamping jigs of the mechanisms. In a preferred embodiment, apparatus components for implementing this automatic operation include a pair of guide plates in each clamping jig that have inner vertically disposed wall surfaces that define therebetween a ninety degree intersection angle or vortex, which is cut off or truncated by a plane oriented at forty-five degrees to the guide bars, to thereby form an opening for insertably receiving the corner of picture frame, with the intersecting channel moldings of the frame aligned with the guide plates.
Each guide plate is provided, near the opening between the inner longitudinal ends of the guide plate, with a sensor which provides an electrical signal indicating that a frame corner molding has been fully inserted into the clamping jig. The electrical signal from each pair of sensors for each of the two clamping jigs are logically ANDed, producing a command signal to initiate automatic operation of the machine only when all three outer sides of the frame channel moldings defining two adjacent corners of the frame are fully inserted into and properly aligned with the guide plates of the two clamping jigs for proper operation of the corner protector folding and attaching operation. This command signal initiates a sequence of operations by which a pair of corner protectors are automatically attached in tandem to the two corners of a picture frame. Upon completion of this automatic operation, the holding clamps of both clamping jigs are automatically released, allowing the frame with a pair of attached corner protectors installed to be withdrawn from engagement with the apparatus. The frame may then be rotated one hundred and eighty degrees in a horizontal plane, and re-inserted into the apparatus to initiate attachment of a pair of corner protectors to the remaining two corners of the picture frame.